Introduction

This chapter describes recent cryogenic forms of North-western Canada and relict forms of the Carpathian Basin to draw comparison between them. The objectives of this chapter are to document them, discuss their paleoenvironmental significance from a process viewpoint and to demonstrate their application for reconstructing the past periglacial history of the central European area.

The theory of climatic geomorphology [4] and uniformitarianism [32] give us possibility to compare different time and location of the Earth in the same geomorphologic system. But the comparison is difficult without correct data on relict permafrost environments and the geographic locations; geomorphologic positions and climate conditions are undoubtedly different. It is essential to realize that recent permafrost areas show a high diversity in environmental settings and the former permafrost environment was multiple changed in time for the same region during the glacial periods [74]. There is a general consensus about the study and interpretation of cryogenic deformation structures (e.g. frost fissures, cryoturbation and involutions) being helpful in paleoenvironmental reconstructions as permafrost indicators [78].

According to former periglacial studies [33, 74] Central Europe was a permafrost area in the last glacial period, but the limit and the zonation of the permafrost are still debated [25, 51, 68, 75]. There are two main periods of continuous permafrost in the paleoenvironmental evolution of Central Europe during the last glacial periods: first c. 72,000-61,000, second c. 27,000-17,000 B.P. [74].

Pleistocene periglacial activity forms an important component of the landscape of the Carpathian Basin [61]. During the glacial periods of the Pleistocene, the Basin was subject to a cryogenic environment that produced various relict periglacial features [27, 48, 65]. The reason for the cold climate during these glacial periods is the Basin's unique geographic setting. The Carpathians, which surrounds this large basin, creates an almost closed climatic situation, producing climatic conditions not found elsewhere in Europe. In effect, Krivan [30] and Dylik [8] seem to imply that the climate in Hungary during the glacial periods of the Pleistocene was somewhat similar to the recent climate of the dry tundra regions of North Siberia. But according to other researchers, the Carpathian Basin was mostly devoid of continuous permafrost during the Pleistocene [6, 33, 70]. Previous researches described so many relict forms in different geomorphic positions [5, 8, 27, 46, 47, 55], but none of these have been revised according to the most recent research methods and permafrost nomenclature. Our review, however, addresses past periglacial processes and their coupling to paleoclimate.

Our interpretation of the periglacial deformations investigated is based on: (a) detailed field observations and (b) a synthesis of published data. Polygenetic forms were analyzed using criteria defined for the periglacial structures. We made classical geomorphologic sketches about locations to identify the geomorphic positions of cryogenic features and connections to their environment (Table 1). Sections were cleaned and described using sedimentological and pedological criteria, with respect of the topographical/geomorphologic location and available moisture. Samples were analyzed for physical and chemical properties and for grain-size analyses and optically stimulated luminescence dating (the latter was done only on Hungarian samples). For OSL dating, samples were collected from individual fill units and additional samples were collected for moisture content and background radiation measurement. The samples were dated at the Geological Institute of Hungary.

Table 1. Geomorphic positions of relict cryogenic features in Hungary.

Geomorphic

Patterned

Ice-wedge

Cryoturbation

Sand wedges

positions

ground

pseudomorphs

Lower terraces

few

common

common

none

Higher terraces

few

localized

few

common

Alluvial fans

common

few

very common

few

Aeolian sandy surfaces

none

none

few

none

Gentle slopes

none

none

common

none

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